Class: Hash

Inherits:
Object show all
Defined in:
activesupport/lib/active_support/core_ext/object/blank.rb,
activesupport/lib/active_support/json/encoding.rb,
activesupport/lib/active_support/core_ext/hash/diff.rb,
activesupport/lib/active_support/core_ext/hash/keys.rb,
activesupport/lib/active_support/core_ext/hash/slice.rb,
activesupport/lib/active_support/core_ext/hash/except.rb,
activesupport/lib/active_support/core_ext/hash/deep_merge.rb,
activesupport/lib/active_support/core_ext/object/to_param.rb,
activesupport/lib/active_support/core_ext/object/to_query.rb,
activesupport/lib/active_support/core_ext/hash/conversions.rb,
activesupport/lib/active_support/core_ext/hash/reverse_merge.rb,
activesupport/lib/active_support/core_ext/array/extract_options.rb,
activesupport/lib/active_support/core_ext/hash/indifferent_access.rb

Overview

:nodoc:

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.from_xml(xml) ⇒ Object



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# File 'activesupport/lib/active_support/core_ext/hash/conversions.rb', line 77

def from_xml(xml)
  typecast_xml_value(unrename_keys(ActiveSupport::XmlMini.parse(xml)))
end

Instance Method Details

#as_json(options = nil) ⇒ Object

:nodoc:



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# File 'activesupport/lib/active_support/json/encoding.rb', line 194

def as_json(options = nil) #:nodoc:
  if options
    if attrs = options[:only]
      slice(*Array.wrap(attrs))
    elsif attrs = options[:except]
      except(*Array.wrap(attrs))
    else
      self
    end
  else
    self
  end
end

#assert_valid_keys(*valid_keys) ⇒ Object

Validate all keys in a hash match *valid keys, raising ArgumentError on a mismatch. Note that keys are NOT treated indifferently, meaning if you use strings for keys but assert symbols as keys, this will fail.

Examples

{ :name => "Rob", :years => "28" }.assert_valid_keys(:name, :age) # => raises "ArgumentError: Unknown key(s): years"
{ :name => "Rob", :age => "28" }.assert_valid_keys("name", "age") # => raises "ArgumentError: Unknown key(s): name, age"
{ :name => "Rob", :age => "28" }.assert_valid_keys(:name, :age) # => passes, raises nothing

Raises:

  • (ArgumentError)


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# File 'activesupport/lib/active_support/core_ext/hash/keys.rb', line 41

def assert_valid_keys(*valid_keys)
  unknown_keys = keys - [valid_keys].flatten
  raise(ArgumentError, "Unknown key(s): #{unknown_keys.join(", ")}") unless unknown_keys.empty?
end

#deep_merge(other_hash) ⇒ Object

Returns a new hash with self and other_hash merged recursively.



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# File 'activesupport/lib/active_support/core_ext/hash/deep_merge.rb', line 3

def deep_merge(other_hash)
  dup.deep_merge!(other_hash)
end

#deep_merge!(other_hash) ⇒ Object

Returns a new hash with self and other_hash merged recursively. Modifies the receiver in place.



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# File 'activesupport/lib/active_support/core_ext/hash/deep_merge.rb', line 9

def deep_merge!(other_hash)
  other_hash.each_pair do |k,v|
    tv = self[k]
    self[k] = tv.is_a?(Hash) && v.is_a?(Hash) ? tv.deep_merge(v) : v
  end
  self
end

#diff(h2) ⇒ Object

Returns a hash that represents the difference between two hashes.

Examples:

{1 => 2}.diff(1 => 2)         # => {}
{1 => 2}.diff(1 => 3)         # => {1 => 2}
{}.diff(1 => 2)               # => {1 => 2}
{1 => 2, 3 => 4}.diff(1 => 2) # => {3 => 4}


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# File 'activesupport/lib/active_support/core_ext/hash/diff.rb', line 10

def diff(h2)
  dup.delete_if { |k, v| h2[k] == v }.merge!(h2.dup.delete_if { |k, v| has_key?(k) })
end

#encode_json(encoder) ⇒ Object



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# File 'activesupport/lib/active_support/json/encoding.rb', line 208

def encode_json(encoder)
  "{#{map { |k,v| "#{encoder.encode(k.to_s)}:#{encoder.encode(v)}" } * ','}}"
end

#except(*keys) ⇒ Object

Return a hash that includes everything but the given keys. This is useful for limiting a set of parameters to everything but a few known toggles:

@person.update_attributes(params[:person].except(:admin))

If the receiver responds to convert_key, the method is called on each of the arguments. This allows except to play nice with hashes with indifferent access for instance:

{:a => 1}.with_indifferent_access.except(:a)  # => {}
{:a => 1}.with_indifferent_access.except("a") # => {}


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# File 'activesupport/lib/active_support/core_ext/hash/except.rb', line 14

def except(*keys)
  dup.except!(*keys)
end

#except!(*keys) ⇒ Object

Replaces the hash without the given keys.



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# File 'activesupport/lib/active_support/core_ext/hash/except.rb', line 19

def except!(*keys)
  keys.each { |key| delete(key) }
  self
end

#extract!(*keys) ⇒ Object



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# File 'activesupport/lib/active_support/core_ext/hash/slice.rb', line 33

def extract!(*keys)
  result = {}
  keys.each {|key| result[key] = delete(key) }
  result
end

#extractable_options?Boolean

By default, only instances of Hash itself are extractable. Subclasses of Hash may implement this method and return true to declare themselves as extractable. If a Hash is extractable, Array#extract_options! pops it from the Array when it is the last element of the Array.



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# File 'activesupport/lib/active_support/core_ext/array/extract_options.rb', line 7

def extractable_options?
  instance_of?(Hash)
end

#reverse_merge(other_hash) ⇒ Object

Allows for reverse merging two hashes where the keys in the calling hash take precedence over those in the other_hash. This is particularly useful for initializing an option hash with default values:

def setup(options = {})
  options.reverse_merge! :size => 25, :velocity => 10
end

Using merge, the above example would look as follows:

def setup(options = {})
  { :size => 25, :velocity => 10 }.merge(options)
end

The default :size and :velocity are only set if the options hash passed in doesn't already have the respective key.



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# File 'activesupport/lib/active_support/core_ext/hash/reverse_merge.rb', line 17

def reverse_merge(other_hash)
  other_hash.merge(self)
end

#reverse_merge!(other_hash) ⇒ Object Also known as: reverse_update

Performs the opposite of merge, with the keys and values from the first hash taking precedence over the second. Modifies the receiver in place.



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# File 'activesupport/lib/active_support/core_ext/hash/reverse_merge.rb', line 23

def reverse_merge!(other_hash)
  merge!( other_hash ){|k,o,n| o }
end

#slice(*keys) ⇒ Object

Slice a hash to include only the given keys. This is useful for limiting an options hash to valid keys before passing to a method:

def search(criteria = {})
  assert_valid_keys(:mass, :velocity, :time)
end

search(options.slice(:mass, :velocity, :time))

If you have an array of keys you want to limit to, you should splat them:

valid_keys = [:mass, :velocity, :time]
search(options.slice(*valid_keys))


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# File 'activesupport/lib/active_support/core_ext/hash/slice.rb', line 15

def slice(*keys)
  keys = keys.map! { |key| convert_key(key) } if respond_to?(:convert_key)
  hash = self.class.new
  keys.each { |k| hash[k] = self[k] if has_key?(k) }
  hash
end

#slice!(*keys) ⇒ Object

Replaces the hash with only the given keys. Returns a hash contained the removed key/value pairs

{:a => 1, :b => 2, :c => 3, :d => 4}.slice!(:a, :b) # => {:c => 3, :d =>4}


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# File 'activesupport/lib/active_support/core_ext/hash/slice.rb', line 25

def slice!(*keys)
  keys = keys.map! { |key| convert_key(key) } if respond_to?(:convert_key)
  omit = slice(*self.keys - keys)
  hash = slice(*keys)
  replace(hash)
  omit
end

#stringify_keysObject

Return a new hash with all keys converted to strings.



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# File 'activesupport/lib/active_support/core_ext/hash/keys.rb', line 3

def stringify_keys
  dup.stringify_keys!
end

#stringify_keys!Object

Destructively convert all keys to strings.



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# File 'activesupport/lib/active_support/core_ext/hash/keys.rb', line 8

def stringify_keys!
  keys.each do |key|
    self[key.to_s] = delete(key)
  end
  self
end

#symbolize_keysObject Also known as: to_options

Return a new hash with all keys converted to symbols, as long as they respond to to_sym.



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# File 'activesupport/lib/active_support/core_ext/hash/keys.rb', line 17

def symbolize_keys
  dup.symbolize_keys!
end

#symbolize_keys!Object Also known as: to_options!

Destructively convert all keys to symbols, as long as they respond to to_sym.



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# File 'activesupport/lib/active_support/core_ext/hash/keys.rb', line 23

def symbolize_keys!
  keys.each do |key|
    self[(key.to_sym rescue key) || key] = delete(key)
  end
  self
end

#to_param(namespace = nil) ⇒ Object Also known as: to_query

Converts a hash into a string suitable for use as a URL query string. An optional namespace can be passed to enclose the param names (see example below).

Examples

{ :name => 'David', :nationality => 'Danish' }.to_param # => "name=David&nationality=Danish"

{ :name => 'David', :nationality => 'Danish' }.to_param('user') # => "user[name]=David&user[nationality]=Danish"


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# File 'activesupport/lib/active_support/core_ext/object/to_param.rb', line 44

def to_param(namespace = nil)
  collect do |key, value|
    value.to_query(namespace ? "#{namespace}[#{key}]" : key)
  end * '&'
end

#to_xml(options = {}) ⇒ Object

Returns a string containing an XML representation of its receiver:

{"foo" => 1, "bar" => 2}.to_xml
# =>
# <?xml version="1.0" encoding="UTF-8"?>
# <hash>
#   <foo type="integer">1</foo>
#   <bar type="integer">2</bar>
# </hash>

To do so, the method loops over the pairs and builds nodes that depend on the values. Given a pair key, value:

  • If value is a hash there's a recursive call with key as :root.

  • If value is an array there's a recursive call with key as :root, and key singularized as :children.

  • If value is a callable object it must expect one or two arguments. Depending on the arity, the callable is invoked with the options hash as first argument with key as :root, and key singularized as second argument. Its return value becomes a new node.

  • If value responds to to_xml the method is invoked with key as :root.

  • Otherwise, a node with key as tag is created with a string representation of value as text node. If value is nil an attribute “nil” set to “true” is added. Unless the option :skip_types exists and is true, an attribute “type” is added as well according to the following mapping:

    XML_TYPE_NAMES = {
      "Symbol"     => "symbol",
      "Fixnum"     => "integer",
      "Bignum"     => "integer",
      "BigDecimal" => "decimal",
      "Float"      => "float",
      "TrueClass"  => "boolean",
      "FalseClass" => "boolean",
      "Date"       => "date",
      "DateTime"   => "datetime",
      "Time"       => "datetime"
    }

By default the root node is “hash”, but that's configurable via the :root option.

The default XML builder is a fresh instance of Builder::XmlMarkup. You can configure your own builder with the :builder option. The method also accepts options like :dasherize and friends, they are forwarded to the builder.



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# File 'activesupport/lib/active_support/core_ext/hash/conversions.rb', line 57

def to_xml(options = {})
  require 'active_support/builder' unless defined?(Builder)

  options = options.dup
  options[:indent]  ||= 2
  options[:root]    ||= "hash"
  options[:builder] ||= Builder::XmlMarkup.new(:indent => options[:indent])

  builder = options[:builder]
  builder.instruct! unless options.delete(:skip_instruct)

  root = ActiveSupport::XmlMini.rename_key(options[:root].to_s, options)

  builder.__send__(:method_missing, root) do
    each { |key, value| ActiveSupport::XmlMini.to_tag(key, value, options) }
    yield builder if block_given?
  end
end

#with_indifferent_accessObject

Returns an ActiveSupport::HashWithIndifferentAccess out of its receiver:

{:a => 1}.with_indifferent_access["a"] # => 1


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# File 'activesupport/lib/active_support/core_ext/hash/indifferent_access.rb', line 9

def with_indifferent_access
  ActiveSupport::HashWithIndifferentAccess.new_from_hash_copying_default(self)
end